Java-ws and object extension

Hi all,
I've a little problem determine my impossibility to use object extension in return objects of WS. I'm using java7 platfform with glassfish 3.1.2 and netbeans ide.
I have a BaseClass as base responder. Any object, for example UserList, put out from any of my services is an extension of the BaseClass. BaseClass has only two properies: error and messageId.

This is an xml response of web service when UserList extend BaseClass

This is an xml response of web service when UserList2 has same properties of UserList but not extend BaseClass, properties error and messageId are declared inside UserList2 method.

Has you can see in first example error and messageId tags are outside UserList, in second example error and messageId are inside UserList2.

When import UserList in Flash or .Net error and messageId are lost and result object is like User[] or a List of User
When import UserList2 in Flash or .Net result object is a UserList2 contains a List of User and error and messageId.

This issue I've found regarding in my experience extended objects: properties came from an object BObject are always lost in WS representation another object EObject extends BObject. This issue regards surely Flash and .Net clients. Java clients are ok.
WS are generated automatically from netbeans.
Clients, flash and .net, import automatically WS from server.